This program project remains as in previous years directed toward acquiring a better understanding of the molecular organization of cell membranes and of synaptic structures. Several specific highly organized membranes in situ and in isolation will be studied by multiple electron microscopic (EM), x-ray diffraction and biochemical methods. The most highly ordered ones along with catalase as a test object and model membranes will be studied by the low beam EM methods of Unwin and Henderson at 25 degrees C and STEM methods at lowered temperature. Major limitations of the freeze-fracture-etch technique will be attacked by the development of better specimen freezing methods, higher resolution metallic replication techniques and double replica techniques that can be used with higher freezing rate methods. Model systems of multilayers of lipids and proteins will be prepared by lifting monolayers from a Langmuir through successively onto Epon substrates and studied by EM and x-ray diffraction techniques. These studies will be correlated with studies of the properties of black lipid films and of bilayer vesicles. Another aspect of the program aims at better understanding of the mechanism of assembly of microtubules and of the structural organization of varies as proteins. These latter studies will be done by x-ray diffraction, EM and biochemical techniques. Studies of the molecular organization of maculae communicantes (gap junctions) isolated from liver will be carried out by a combined biochemical, electron microscopic and x-ray diffraction approach. A three-dimensional analysis by low dose electron microscopy is planned. Correlated x-ray diffraction studies will be done. Studies of the structure of retinal rod outer segments aimed at elucidating the mechanism of action of rhodopsin will be pursued as will studies of the Halobacterium purple membrane. Studies of the membrane external surface binding protein ligatin will continue using retinal and optic tectal cells as sources.